Sen. Marco Rubio will NOT follow in the footsteps of Donald Trump's son and boycott the NFL over anthem demonstrations ... telling TMZ Sports players have every right to protest.
"Look, I think players are Americans," Rubio said. "They have free speech rights to say whatever they want."
The Dallas Cowboys -- who have famously NEVER had a player kneel for the anthem -- now have players considering taking a knee for the pregame song during their season-opener on Sunday ... and that really angered Eric Trump this week.